Disintegration determination

Determine the number of disintegrations per second for radioactive sources of each of the following activities ... 

Addition of such a complexing agent increases the total number of species present in the solution, affecting thus its viscosity — a phenomenon allowing one to determine the degree of disintegration. The concentration of P as a function of [S] and ofc — the total concentration of the polymers in whatever form, is determined by the stoichiometric equation ... 

The strong influence of the specific impeller power P/V and of the impeller type on the disintegration of floes can be seen from these curves, so that the effects of the operating conditions and the reactor type can be determined with satisfactory accuracy. The disintegration kinetics are complex, and show an exponential decrease in particle size with time. 

The results presented here were found by investigations with a special cyUn-der system [45,48]. This system was constructed for an existing Searle viscosimeter (rotation of inner cylinder), such that the gap widths were large in relation to the reference floe diameter of the floccular system used, so that the formation of the floes and their disintegration in the cylinder system are not impaired. For this system, with r2 = 22 mm, rj = 20.04 mm, and Li = 60 mm (r2/ri > 1.098), the following Newton number relationships were determined from the experimental values collected by Reiter [38] for the Taylor number range of 400 < Ta < 3000 used here ... 

Figure 11 shows the reference floe diameter for viscometers as a function of shear stress and also the comparison with the results for stirred tanks. The stress was determined in the case of viscosimeters from Eq. (13) and impeller systems from Eqs. (2) and (4) using the maximum energy density according to Eq. (20). For r > 1 N/m (Ta > 2000), the disintegration performance produced by the flow in the viscosimeter with laminar flow of Taylor eddies is less than that in the turbulent flow of stirred tanks. Whereas in the stirred tank according to Eq. (4) and (16b) the particle diameter is inversely affected by the turbulent stress dp l/T, in viscosimeters it was found for r > 1.5 N/m, independently of the type (Searle or Couette), the dependency dp l/ pi (see Fig. 11). 

The relationship dp dp found for the floccular system and the oil/ water emulsion, with b = -l/3, confirms the theoretically derived Eq. (16b) where particle disintegration is determined by the turbulent eddies in the dissipation range. 

Why do stmctures tend to disintegrate, and why must living organisms spend much time and effort creating organized stmctures The first law of thermod3Tiamics, presented in Chapter 6, requires that energy must be conserved but places no restrictions on what direction a process must take. The explanation for why processes have preferred directions lies in the second law of thermodynamics, which we describe in this chapter. The second law lets us determine whether or not a chemical process can occur. It also lets us determine whether a... 

Savignac, J. R., Fairhurst, C. W. Ryge, G. (1965). Strength, solubility and disintegration of zinc phosphate cement with clinically determined powder/liquid ratio. Angle Orthodontics, 35, 126-30. 

Table II shows data obtained by sequential hexanes and ethanol extractions of the desilylated networks. Attempts to extract the networks prior to desilylation failed because the samples swelled to such a great degree that they lost their mechanical integrity and disintegrated. The amount of hexanes extractable material is less than 3% in all cases which indicates high copolymerization yields. Ethanol extractables were not determined because the presence of the byproducts of the desilylation, which are in the ethanol, would have given artificially high readings.

Determination of the time for a tablet to disintegrate when immersed in some test fluid has been a requirement in most compendia for many years. For many years, it was the only test available to evaluate the release of medicaments from a dosage unit. We now recognize the severe limitations of such tests in assessing this property—hence, the introduction of dissolution rate requirements. 

We calculated in Example 22.4 that 0.500 g would remain. That means that 4.00 g - 0.500 g = 3.50 g of the isotope will have disintegrated. (Most of the 3.50 g will produce some other isotope.) Notice the difference in the wording of Examples 22.4 and 22.5. How much remains is determined from the half-life how much decomposes is determined from the original quantity and how much remains. 

Horrocks, D. L., Low-Level Alpha Disintegration Rate Determinations with a One-Multiplier Phototube Liquid Scintillation Spectrometer,... 

Figure 1 applies to pyrolysis in which the wood temperature is raised from 100 C in about 10 h to various final temperatures. The weight losses, depicted as volatiles, and solid residues have been determined after the trials, and originate mainly from Klason, v. Heidenstam, and Norlin (4), under consideration of data published by Goos (18) and Stamm (19). Measurements on small samples by Beall and Eickner (20), LeVan and Schaffer (21), and Elder (22) have been compared. Up to about 275 or 300 C — the temperature range in which cellulose rapidly disintegrates — increased final trial temperatures cause increased increments of volatiles beyond 300 C the increments steadily diminish. 

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